Thread-tension device for sewing machines



` Feb. 22, 1949. F. PARRY ET AI.

THREAD-TENSION DEVICE FOR SEWING MACHINES 2 sheeft-sneet 1 Filed Feb. 9,1946 Feb. 22, 1949` F, PARRY ET AL 2,462,812

THREAD-TENSION DEVICEA FOR SEWING MAHINES Filed Feb. 9, 1946 2Sheets-Sheet 2 Patented Feb. 22, 1949 UNITED Srl'lf'AfI'ELS THREAD-TENSION DEVICE FOR SEWING MACHINES Frank Barry and Berthold P. Pinkvoss,Bridgeport, Conn., assignors to The Singer Manufacturing Company,Elizabeth, N. J., a corporation of New. Jersey Application February 9,1946, Serial No. 646,603

10 Claims.

This invention relates to thread-tension devices for sewing machinesand, more particularly, to thread-tension devices of the two-diskreleasable type for tensioning the needle-thread.

Devices of the present type heretofore used were providedy with anabutment-plate formed with a rotation-restraining nger which was adaptedto enter an aperture formed in the sewing machine wall. With this typeof construction there was a tendency for the abutmentplate to cantwhenever the'tension-spring pressure was released therefrom, and thusthe rotation-restraining finger sometimes became wedged against theapertured side wall of the machine frame when the spring pressure wasagain applied to the abutment-plate. With the abutmentplate thus heldout of its proper position, the tension unit became inoperative.

The principal object of the-present invention is to` provide a.thread-tension unit which will overcome the above noted difficulty.

Another object of the present invention is to provide a needle-threadtension unit with means to prevent inadvertent unthreading of thecheckspring.

With the above and other objects in view, as will hereinafter appear,the invention comprises the devices, combinations, and arrangements ofparts hereinafter set forth and illustrated in; the accompanyingdrawings of a preferred embodiment of the invention, from whichl the'several` features of the invention and theV advantages-'atltainedthereby will be readily understood by those skilled in the art.

Fig. 1 represents a face view of the needle-bar head of a sewing.machine carryingV a pair of tension devices embodying one form oftheinvention'.

Fig. 2 represents a rearfelevation view of the needle-bar head carryingthe twotensionunits.

Fig. 3 representsan enlarged side View of one form of the tensiondevice.

Fig. 4 represents a longitudinal sectional view of the unit shown inFig. 3V.

Fig. 5 represents an enlarged view of a second form of tension device.

Fig. 6 represents a disassembled perspective view of the tension deviceshown in Fig..3.

Fig. 7 represents aV disassembled perspective view of elements forming apart of that device shown in Fig. 5.

Fig; 8 represents a sectional View taken substantially along line 8--8of Fig. 4;

Fig. 9V represents a sectional View taken substantially. along lineQ-S'of Fig. 5.

Fig. 10 represents a longitudinal sectional' view of. the` unit showninv Fig. 3, but with the tension: disks intheir. separateclv or openposition.

Thesewing machine, illustrated:Y in the` draw.'- ings., has` a. frameincluding a work-supporting bed-plate indicated by line i9 and a hollowbracket-arm head il. Journaled for vertical reciprocation in thebracket-arm head Il is a needle-bar l2 carrying at its lower end a pairvof needles of which only one, designated by the numeral E3, is shown,said needle-bar l2 lbeing endwise reciprccated vertically by any usualor suitable actuating connections with a horizontally disposed rotaryactuating shaft Mi. Cooperating with the needles I3 in the formation oflockstitches, are rotary loop-takers (not shown) which may be of anysuitable construction.

Mounted on the head Il are the usual rotary take-up disks l5 and lcarrying the take-up elements I? and E8, respectively, as well as thethread-confining rings I'S and 253.

Each of two needle threads 2 l, drawn from its supply (not shown), isthreaded through a tube 22 mounted upon the bracket-arm head i l. Fromthe lower ends of the tubes 22, the threads 2l are each led about one ofthe two tension devices designated generally as 23, from whence thethreads are directed upwardly to be disposed between the take-up disk Iand its associated thread-confining ring 2Q tol overlie thethreadengaging elements i8. From the elements it, the threads passforwardly between a face-plate 24 and the machine-head ll, over thethreadengaging elements li between the disk l5 and its associated ringi9. From the elements il, the threads `pass downwardly successivelythrough the face-plate thread-guides 25 and 26 to be directed to theproper needle.

Further explanation of the present rotary take-up is not deemednecessary and, for a cornplete disclosure of the same, reference may behad to the U. S. patent of S. Zonis, No. 2,385,960, Oct. 2, 1945.

Referring more particularly to the present invention, each of thetension devices 23 comprises a cup-shaped support or sleeve member 2which is seated within one of. two apertures 28 formed. in the head E i.A set-screw 29, threaded into the head, engages an annular groove 30 inthe sleeve member 21 for the purpose of securing the latter elementwithin the aperture 2B. In the rear portion of the sleeve 2l is formedan aper ture 3ll for entrance by the reduced rear end` portion 32 of athreaded stud or arbor member 33 which is secured within the aperture 3lby means of a set screw 34.

Slidably mounted upon an intermediate portion of the arbor 33 is anapertured abutmentf plate 35 provided with two ears 38. which are bentabout a ycircumferential ila-nge 3l formed on thesleeve 2l. the flange3l at diametrically oppositev sides,

thereof and` functionI as guides which. permit the`V abutment-plate toturn; about the. arbor 33' but These ears: 33 preferably engage:

which prevent; the `plate from canting on the arbor.

Extending rearwardly from the peripheral p01'- tion of theabutment-plate is a motion-restraining nger 38 which is adapted to enterone oi the two apertures 39 formed within the face portion of the headH.

Extending forwardly from the peripheral portion of the abutment-plate 35is a thread-guiding finger 46, the function of which will be hereinafterdescribed. Also extending forwardly from the peripheral portion of theplate is a thread-confining nger 4l which forms, in conjunction with theplate proper, a thread-conning notch or thread guide 42.

Abutting against the outboard face of the abutu ment-plate is an innerdisk 43 of a pair of spring biased and centrally aperturedthread-tension disks mounted upon the arbor 33, the outer disk beingdesignated by the number 44. Also mounted upon the arbor 33 is ananchor-disk l5 having a diameter-bar 4S passing through a slot si formedin the outer end of the arbor 33. lThe outer endportion of the arbor 33is also provided with threads 48 for a tension-adjusting thumb-nut lilfor the purpose of forcing a bee-hive spring d against the anchor-disk45 which transmits the pressure of the spring directly against the disks43 and 4,4. By adjusting the thumb-nut 49 along the threaded portion ofthe arbor, the pressure existing between the disks 43 and it may bevaried.

An endwise movable tension-release pin 5i is supported in a longitudinalbore 52 of the arbor 33. The forward end of this pin 5E is adapted toengage the diameter-bar 46 of the disk 45 and rear end thereof isadapted to be engaged by a cam-lever 53 which is actuated by the usualpresser-foot lifting lever 54. This tension-release pin 5I operates inthe usual manner in that it is adapted to be pushed by the cam-lever ina direction to relieve the tension-disks 43 and 44 of the pressure ofthe tension-spring 56. Fig. 1Q illustrates the positions assumed by thedisks when relieved of the spring pressure.

Referring to Fig. 4, the sleeve 21 has a cylindrical aperture 55 inwhich is disposed an enlarged portion 56 of the arbor member 33 having aslot 51 formed longitudinally thereof. Coiled about this enlargedportion 56 is the usual torsion check-- spring 58, one end 56 of whichis anchored in the slot 51. The other end of the torsion check-spring isextended outwardly at 6) through a segmental clearance opening Z1 formedin the outer end of the sleeve 21. At its free end, the outwardlyextending arm 60 of the spring is bent backwardly to form athread-engaging loop 6l. The arm 6e of the check-spring is limited inits movement in one direction by a stop-ledge 62 forming one wall of thesegmental opening 21 of the sleeve 21. Circular adjustment of the sleeve21, within the machine aperture 28, determines the stopped position ofthe looped end 6| of the check-spring. lThe tension of the check-springmay be adjusted by loosening the set-screw 34 and turning the arbor 33in its socket in the supporting sleeve 2l and by subsequently tighteningthe screw 34.

Referring to Fig. 6, the flange 31 of the sleeve 21 is provided with anotch 63 for the purpose of facilitating placement of the abutment-plate35 in its proper position relative to the sleeve. Thus, when assemblingthe sleeve and abutment-plate together, one of the ears 36 of the latterunit may enter the notch 63, thereby permitting the ears 36 to be bentprior to the assembly operation.

4 Referring to Fig. 1, the tension unit is disclosed in its operablecondition. The thread 2l passes over the thread-guiding finger 46, thenabout the arbor 33 between the disks 43 and 44, and then is directedthrough the thread-confining notch 42 from which it passes under andabout the checkspring before being directed to the take-up elements. Bythus passing the thread about the thread-guiding finger it beforepassing the same between the disks, the thread is prevented from foulingthe check-spring.

From the above description, it is to be understood that the presentabutment-plate 35, with its guiding ears and motion-restraining finger,is not only restrained from turning about the sleeve 21 but, at the sametime, -it has no tendency to cant.

Considered circumferentially of the guard-plate the stop-nger 33 thereofis located between the thread-guiding nger 4t and the thread-conningnotch 42; the latter being located between the stop-ledge S2 of thesleeve 21 and the stopfinger 3. As the arm 66 of the check-spring isconfined to vibratory movement between the stopledge 32 and thestop-finger 38, the check-spring Ycannot foul the portion of the threaddirected from the tube 22 to the tension device by the thread-guidingfinger dil which is disposed at the side of the stop-nger 38 opposite tothe checkspring side thereof.

Figs. 5, 7 and 9 disclose a modified form of the present tension unit.This modified unit is exactly the same as the above described unit butfor an addition of a check-spring guard element.

Referring to Figs. 5 and 7, a check-spring guard element 64,V having agenerally dished shape, is inserted between the outer disk 44 and theanchor-disk 45. Projecting upwardly from the periphery of this dishedelement are a pair of ears 65 which, when the element is assembled,embrace the thread-guiding nger 46, thus to prevent rotation of theelement. Also provided in the periphery of this element is a slot 66through which extends the free end portion 61 of the check-spring 58.Referring to Fig. 9 it is to be seen that by so inserting the portion 61of the check-spring within the slot 66, the possibility of the thread 2ldisengaging itself from the check-spring loop 60 becomes rather remote.Therefore, the present guard 64 is particularly useful whenever aneX-cess of slack occurs in the thread 2l, as this element will preventinadvertent unthreading of the check-spring.

Having thus set forth the nature of the invention, what we claim hereinis:

1. In a thread tensioning device for sewing machines, a support formedwith a flange, an arbor carried by said support, spring-pressed opposedtension-disks mounted upon said arbor, a thread-guide carryingabutment-plate disposed adjacent one of said tension-disks, andinterlocking means between the flange of the support and theabutment-plate providing for relative turning adjustment of said supportand abutment-plate and for confining said abutment-plate againstsidewise movement.

2. In a thread tensioning device for sewing machines, a cylindricalsupporting member having a circumferential flange, an arbor carried bysaid supporting member, releasable thread tensioning means mounted uponsaid arbor, a thread-guide carrying abutment-plate disposed adjacentsaid thread tensioning means,'and ears extending from saidabutment-plate and bent about said ange of the supporting member.

3. In a thread tensioning device for sewing'- machines, a supportingmember having a stopshoulder, an arbor carried by and projecting fromsaid supporting member, releasable thread tensioning means carried bysaid arbor, a threadguide carrying abutment-plate disposed between saidtensioning means and said supporting member, a check-spring having athread-controlling arm yieldingly engaging said stop-shoulder, andabutment-plate confining means comprising interlocking members betweensaid support and said abutment plate which provide for relative turningadjustment of said supporting member and abutment-plate about thelongitudinal axis of said arbor and for restraining said abutmentplateagainst sidewise movement upon release of said thread tensioning means.

4. A sewing machine tension device having an arbor, thread tensioningmeans mounted on said arbor, a thread-controlling check-spring havingone end thereof anchored to said arbor and having a thread-engagingfree-end portion, an abutment-plate disposed at one side of saidtensioning means and provided with a thread-guide in the region of thethread-engaging portion of said check-spring, a guard-plate mounted uponsaid arbor at the opposite side of said tensioning means in position tohouse the free end of said check-spring, and interengaging means carriedby said abutment-plate and guard-plate for preventing relative turningmovement thereof about said arbor.

5. A sewing machine tension device having an arbor, thread tensioningmeans mounted on said arbor, a thread-controlling check-spring anchoredto said arbor at one side oi said tensioning means, said check-springhaving a free end thread-engaging portion bent about and extending tothe opposite side of said tensioning means, means housing the free endof said check-spring and consisting of a anged guard-plate mounted uponsaid arbor for movement endwise thereof, and means comprising astationary finger eX- tending across said tensioning means forrestraining said guard-plate from turning about said arbor.

6. A sewing machine tension device having an arbor, thread tensioningmeans mounted on said arbor, a thread-controlling check-spring having athread-engaging free end portion, an abutmentplate at one side of saidtensioning means and provided with a thread-guide for directing thethread from said tensioning means to said checkspring, means housing thefree end of said checkspring and comprising a guard-plate mounted onsaid arbor at the side of said tensioning means remote from saidabutment-plate, and a nger connecting and providing for relativemovement of said abutment-plate and guard-plate.

7. In a thread tensioning device for sewing machines, an arbor, threadtensioning means carried by said arbor, a thread-controlling checkspringhaving one end anchored to said arbor and having a yieldingthread-engaging portion, a stationary abutment-plate provided withlaterally extending stop means limiting movement of the thread-engagingportion of the checkspring responsively to the pull of the threadthereupon, a laterally extending lead-in threadguide carried by saidabutment-plate at one side of said check-spring stop means, and alaterally extending lead-out thread-guide carried by said abutment-plateat the other side of said checkspring stop means.

8. In a thread tensioning device for sewing machines, an arbor, threadtensioning means carried by said arbor, a thread-controlling checkspringhaving a yielding thread-engaging portion, and an abutment platedisposed adjacent said thread tensioning means, said abutment platehaving a stop-finger projecting laterally from one side of said plateand disposed to be engaged by said check-spring, and a pair ofthread-guides projecting from the other side of said abutmentplate andspaced on opposite sides of said stopfinger.

9. In a thread tensioning device for sewing machines, an arbor, threadtensioning means carried by said arbor, a thread-controlling checkspringhaving one end anchored to said arbor at one side of said threadtensioning means and having a free end thread-engaging portion bentabout and extending to the opposite side of said thread tensioningmeans, and means for housing the free end of said check-spring, saidmeans including a guard-plate formed with a laterally extending flangeslotted to provide an opening through which the free end of thecheck-spring extends, and means for restraining said guardplate againstturning about said arbor.

10. A releaseable tension device for sewing machines, comprising, asupporting sleeve having at one end thereof a clearance opening and acircumferential flange, an arbor mounted in said sleeve for turningadjustment and extending through the anged end of said sleeve, a pair ofopposed tension-disks mounted upon said arbor for movement endwisethereof, a check-spring embracing said arbor within said sleeve, saidcheck-spring being anchored to said arbor and having a reversely bentfree end portion extending through said clearance opening of thesupporting sleeve and about the peripheries of said tension-disks,thereby to provide a yieldable thread-engaging loop, an abutment-platemounted upon said arbor between said tension-disks and the flanged endof said sleeve, said abutmentplate having a primary stop-fingeroverhanging said sleeve and an oppositely directed secondary stop-fingeroverhanging said tension-disks, means for preventing canting of saidabutmentplate comprising abutment-plate ears embracing said flange, athread-confining nger extending from said abutment plate toward andhaving its free end spaced from said secondary stop-iinger, aguard-plate mounted upon said arbor at the side of said tension-disksopposite to said abutment-plate, said guard-plate having a slottedflange entered by and housing the free end of said check-spring, andsaid guard-plate having a peripheral stop-notch entered by saidsecondary stop-finger, and spring means for yieldingly pressing saidtension-disks towards each others.

FRANK PARRY. BERTHOLD P. PINKVOSS.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 994,509 Gray June 6, 19111,862,658 Chason June 14, 1932 2,131,005 Chason Sept. 20, 1938

